Take four people — Alex, Maria, John, Sarah — with three expenses: Maria paid $80 for dinner, Alex paid $40 for gas, and John paid $220 for a hotel. Total spent: $340, split four ways is $85 each. Comparing what each person paid to that $85 share gives each person a net balance: Alex is down $45, Maria is down $5, Sarah (who paid for nothing) is down the full $85, and John — having paid $220 against an $85 share — is owed $135. The tool then repeatedly matches whoever owes the most against whoever is owed the most: Sarah pays John $85 (clearing Sarah's debt and covering part of John's), Alex pays John $45, and Maria pays John $5 — three payments that net out exactly.
The naive way to settle a group expense is for every person who owes money to pay every person who's owed money, which can balloon into a lot of separate payments as the group grows. The greedy match above needs at most one fewer payment than there are people, no matter how many separate expenses were entered — the four-person example above settles in exactly three payments, all directed at whoever ended up most out of pocket, rather than a tangle of smaller transfers in every direction.
Not yet — every expense entered here is split equally across everyone in your People list. If someone shouldn't be included in a particular expense, the cleanest workaround is to track that one separately.
No — everything happens in your browser for this session only, nothing is uploaded or stored. Refreshing or closing the tab clears your people and expenses, so use Copy Summary before you leave if you want to keep the result.
Each person's fair share is the total spent divided by the number of people. A person's net balance is what they paid minus their fair share, and the tool then matches people who are owed money with people who owe money so everyone settles up in as few payments as possible.